A device for safeguarding a driven movement element is known from the prior art, for example from EP 1 841 942 B 1. In the case of the device, an electronic unit determines, from the time difference from the first to the second light barrier as a result of the triggering of these light barriers, a time at which a downstream, third light barrier would be registered, and switches the third light barrier into the measurement state in a timely fashion before this event occurs.
The problem addressed by the invention is to propose a safety device and a closing device which make it possible in an improved manner to recognize a risk of collision during the movement of the movement element.